means The slender main stalk of a plant that holds it upright and channels water and nutrients between roots and leaves — or, more broadly, the central supporting shaft of any object.

from From Old English 'stemn' or 'stefn,' meaning the trunk of a tree or the stem of a plant, and tied up with the prow or 'stem' of a ship. It traces back to a Proto-Germanic root (compare Dutch 'stam' and German 'Stamm,' trunk) and is thought to share deep ancestry with words for 'to stand' — fitting for the part that does the standing. The verb 'to stem' meaning 'to stop or hold back' (as in 'stem the tide') is a separate cousin, from Old Norse 'stemma,' to dam up.